1. Field of the Invention
The present invention relates to a printing apparatus which informs a host apparatus of condition changes such as a power-OFF state, out-of-paper state, and the like, and a control method of the apparatus.
2. Related Art
Conventionally, in a printing apparatus of this type, the power switch of a printer is directly connected to a power supply, and when the power switch is turned off, the power supply also goes off immediately. For this reason, since the printer power supply goes off immediately after the printer power switch is turned off, the host apparatus cannot be informed of the power-OFF operation. Even when data to be output still remains upon power OFF of the printer, the host apparatus cannot be informed of it.
In the conventional printing apparatus, even when the remaining paper quantity has changed, the printer engine does not issue any message indicating it, and the printer controller that controls the engine requests status of the engine to detect changes in remaining paper quantity. In a network system that shares a printer, a host apparatus which does not use that printer is also informed of information associated with the remaining paper quantity read out from the engine to the controller.
A conventional network management utility of the host apparatus that uses such a printer issues condition inquiries at given intervals to the printer, thereby detecting condition changes. For this reason, when the printer is connected to the network, some host apparatuses often recognize the printer as an active one although the power supply of that printer is OFF.
Since the remaining paper quantity in the conventional printer is periodically detected by the printer controller, even when the remaining paper quantity has changed, the latest remaining quantity cannot be detected before the next detection. Also, since all the host apparatuses are informed of the detected remaining paper quantity, such information increases the communication traffic of the network.
Also, since the host apparatus periodically acquires condition changes in the conventional printer, accurate condition changes cannot be detected in real time before the next detection even when the conditions of the printer have changed. Also, a host computer can designate neither the types of condition change information of the printer nor the host computers to be informed of that information.